feat: add ATMOS_CI_COMMENTS_ENABLED env var to override ci.comments.enabled

pkg/config/utils.go

@@ -426,6 +426,17 @@ func processEnvVars(atmosConfig *schema.AtmosConfiguration) error {
 		}
 	}
 
+	ciCommentsEnabled := os.Getenv("ATMOS_CI_COMMENTS_ENABLED")
+	if len(ciCommentsEnabled) > 0 {
+		log.Debug(foundEnvVarMessage, "ATMOS_CI_COMMENTS_ENABLED", ciCommentsEnabled)
+		enabled, err := strconv.ParseBool(ciCommentsEnabled)
+		if err != nil {
+			log.Warn("Invalid boolean value for ENV variable; using default.", "ATMOS_CI_COMMENTS_ENABLED", ciCommentsEnabled)
+		} else {
+			atmosConfig.CI.Comments.Enabled = enabled
+		}
+	}
+
 	return nil
 }
 

pkg/config/utils_test.go

@@ -302,6 +302,37 @@ func Test_processEnvVars(t *testing.T) {
 			expectError:  true,
 			errorMessage: "strconv.ParseBool: parsing \"not-a-boolean\": invalid syntax",
 		},
+		{
+			name: "ATMOS_CI_COMMENTS_ENABLED=true enables CI comments",
+			envVars: map[string]string{
+				"ATMOS_CI_COMMENTS_ENABLED": "true",
+			},
+			expectedConfig: schema.AtmosConfiguration{
+				CI: schema.CIConfig{
+					Comments: schema.CICommentsConfig{Enabled: true},
+				},
+			},
+			expectError: false,
+		},
+		{
+			name: "ATMOS_CI_COMMENTS_ENABLED=false disables CI comments",
+			envVars: map[string]string{
+				"ATMOS_CI_COMMENTS_ENABLED": "false",
+			},
+			expectedConfig: schema.AtmosConfiguration{
+				CI: schema.CIConfig{
+					Comments: schema.CICommentsConfig{Enabled: false},
+				},
+			},
+			expectError: false,
+		},
+		{
+			name: "ATMOS_CI_COMMENTS_ENABLED invalid value logs warning without error",
+			envVars: map[string]string{
+				"ATMOS_CI_COMMENTS_ENABLED": "not-a-bool",
+			},
+			expectError: false,
+		},
 	}
 
 	for _, tt := range tests {
@@ -335,6 +366,103 @@ func Test_processEnvVars(t *testing.T) {
 	}
 }
 
+func TestProcessEnvVars_CICommentsEnabled(t *testing.T) {
+	tests := []struct {
+		name    string
+		envVal  string
+		initial bool
+		want    bool
+	}{
+		{
+			name:    "env var true overrides false yaml default",
+			envVal:  "true",
+			initial: false,
+			want:    true,
+		},
+		{
+			name:    "env var false overrides true yaml setting",
+			envVal:  "false",
+			initial: true,
+			want:    false,
+		},
+		{
+			name:    "env var 1 enables CI comments",
+			envVal:  "1",
+			initial: false,
+			want:    true,
+		},
+		{
+			name:    "env var 0 disables CI comments",
+			envVal:  "0",
+			initial: true,
+			want:    false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Setenv("ATMOS_CI_COMMENTS_ENABLED", tt.envVal)
+
+			config := &schema.AtmosConfiguration{
+				Schemas: make(map[string]interface{}),
+				CI: schema.CIConfig{
+					Comments: schema.CICommentsConfig{Enabled: tt.initial},
+				},
+			}
+
+			err := processEnvVars(config)
+			assert.NoError(t, err)
+			assert.Equal(t, tt.want, config.CI.Comments.Enabled)
+		})
+	}
+
+	t.Run("env var not set leaves yaml value unchanged", func(t *testing.T) {
+		// Empty string is treated as unset — env var is not processed.
+		t.Setenv("ATMOS_CI_COMMENTS_ENABLED", "")
+
+		config := &schema.AtmosConfiguration{
+			Schemas: make(map[string]interface{}),
+			CI: schema.CIConfig{
+				Comments: schema.CICommentsConfig{Enabled: true},
+			},
+		}
+
+		err := processEnvVars(config)
+		assert.NoError(t, err)
+		assert.True(t, config.CI.Comments.Enabled)
+	})
+
+	t.Run("invalid env var value logs warning and leaves value unchanged (true)", func(t *testing.T) {
+		t.Setenv("ATMOS_CI_COMMENTS_ENABLED", "not-a-bool")
+
+		config := &schema.AtmosConfiguration{
+			Schemas: make(map[string]interface{}),
+			CI: schema.CIConfig{
+				Comments: schema.CICommentsConfig{Enabled: true},
+			},
+		}
+
+		err := processEnvVars(config)
+		assert.NoError(t, err)
+		assert.True(t, config.CI.Comments.Enabled)
+	})
+
+	t.Run("invalid env var value logs warning and leaves value unchanged (false)", func(t *testing.T) {
+		t.Setenv("ATMOS_CI_COMMENTS_ENABLED", "not-a-bool")
+
+		config := &schema.AtmosConfiguration{
+			Schemas: make(map[string]interface{}),
+			CI: schema.CIConfig{
+				Comments: schema.CICommentsConfig{Enabled: false},
+			},
+		}
+
+		err := processEnvVars(config)
+		assert.NoError(t, err)
+		assert.False(t, config.CI.Comments.Enabled)
+	})
+}
+
 func TestFindAllStackConfigsInPathsForStack(t *testing.T) {
 	stacksPath := "../../tests/fixtures/scenarios/stack-templates-2"
 

website/blog/2026-04-10-ci-comments-env-var.mdx

@@ -0,0 +1,58 @@
+---
+slug: ci-comments-env-var
+title: "Toggle CI PR Comments with an Environment Variable"
+authors: [atmos]
+tags: [enhancement]
+date: 2026-04-10T00:00:00.000Z
+---
+
+You can now enable or disable CI PR comments per-pipeline using the `ATMOS_CI_COMMENTS_ENABLED` environment variable — no config file changes needed.
+
+<!--truncate-->
+
+## What Changed
+
+A new `ATMOS_CI_COMMENTS_ENABLED` environment variable overrides the `ci.comments.enabled` setting in `atmos.yaml`. When set, it takes precedence over the YAML configuration.
+
+```
+ATMOS_CI_COMMENTS_ENABLED=true   # enable PR comments
+ATMOS_CI_COMMENTS_ENABLED=false  # disable PR comments
+```
+
+The variable accepts any standard boolean value (`true`, `false`, `1`, `0`). Invalid values log a warning and leave the YAML setting unchanged.
+
+## Why This Matters
+
+Some CI workflows need different PR comment behavior depending on the context. For example:
+
+- **Scheduled drift-detection runs** should suppress PR comments (there's no PR to comment on)
+- **PR preview pipelines** should post plan summaries as PR comments
+- **Staging deploys** triggered by merge should skip comments
+
+Previously, you had to maintain separate `atmos.yaml` files or use conditional YAML templating to toggle comments. Now it's a single environment variable.
+
+## How to Use It
+
+Set the variable in your CI workflow:
+
+```yaml
+# Post plan summaries as PR comments
+- name: atmos terraform plan
+  env:
+    ATMOS_CI_COMMENTS_ENABLED: "true"
+  run: |
+    atmos terraform plan "$COMPONENT" --stack "$STACK"
+
+# Suppress comments for scheduled runs
+- name: atmos terraform plan (drift detection)
+  env:
+    ATMOS_CI_COMMENTS_ENABLED: "false"
+  run: |
+    atmos terraform plan "$COMPONENT" --stack "$STACK"
+```
+
+The environment variable follows the same precedence as other `ATMOS_*` variables: CLI flags > environment variables > config files > defaults.
+
+## Get Involved
+
+Found an issue or have a feature request? Open an issue on [GitHub](https://github.com/cloudposse/atmos/issues).

website/docs/cli/configuration/ci/comments.mdx

@@ -35,6 +35,8 @@ ci:
     **Requires:** `pull-requests: write` permission (GitHub) or API token with MR notes scope (GitLab)
 
     **Default:** `true`
+
+    **Environment variable:** `ATMOS_CI_COMMENTS_ENABLED` — overrides this setting when set.
   </dd>
 
   <dt>`ci.comments.behavior`</dt>
@@ -52,6 +54,12 @@ ci:
   </dd>
 </dl>
 
+## Environment Variables
+
+| Variable | Description |
+|----------|-------------|
+| `ATMOS_CI_COMMENTS_ENABLED` | Override `ci.comments.enabled` (`true`/`false`). Takes precedence over the YAML configuration when set. |
+
 ## GitHub Actions Permissions
 
 PR comments require the `pull-requests: write` permission:

website/docs/cli/configuration/ci/index.mdx

@@ -113,6 +113,7 @@ Override with the `--ci` flag or `ci.enabled` configuration.
 | Variable | Description |
 |----------|-------------|
 | `ATMOS_CI` | Explicitly enable CI mode (`true`/`false`) |
+| `ATMOS_CI_COMMENTS_ENABLED` | Override `ci.comments.enabled` (`true`/`false`) |
 | `CI` | Standard CI environment variable (set by most CI providers) |
 | `GITHUB_ACTIONS` | Set by GitHub Actions runner |
 | `GITHUB_TOKEN` / `GH_TOKEN` | GitHub API token (required for status checks and PR comments) |